The present invention is related generally to personal watercraft. More specifically, the present invention is related to personal watercraft having adjustable sponsons.
Personal watercraft have become increasingly popular in recent years. A personal watercraft, also known as a xe2x80x9cjet skixe2x80x9d typically has a bottom hull, handle bars for steering, a tunnel within the bottom hull, a jet pump located within the bottom tunnel, and an engine within the hull under the top deck for driving the jet pump. The jet pump typically pulls in water from the front of the tunnel under the boat, and discharges the water at high velocity through a steerable nozzle at the rear of the boat. The handle bars are typically coupled to the nozzle, which is the steering mechanism for the personal watercraft. The watercraft commonly has a straddle-type seat and foot wells disposed on either side of the seat.
Early watercraft often had longitudinal chines running underneath the bottom hull, and sometimes had steps located in the rear portion of the bottom hull, for reducing porpoising by extending the length of the boat while not extending the length of wetted surface. Steering, as previously indicated, was primarily effected by turning the handle bars coupled to the nozzle, which could be steered from side to side to direct the water jet in the desired direction and thereby steer the personal watercraft. The steerable nozzle sometimes had a small rudder on the nozzle, also for aiding in steering the watercraft.
Early personal watercraft sometimes skidded around corners wider than the driver desired. Sometimes, boats would turn 180xc2x0, despite the driver""s intent to make a sharp 90xc2x0 turn. This lack of control at high speeds during aggressive maneuvers was later addressed by adding sponsons to the personal watercraft.
The term xe2x80x9csponsonxe2x80x9d has come to have different meanings in different contexts. Historically, sponsons were floatation devices or outriggers for stabilizing a boat in rough water. The sponsons could be lowered to stabilize a boat in rough water, for example, while fishing. The sponsons could be later raised for traveling through the water. The term sponson has also been used to refer to the outrigger on an outrigger canoe. As used in the personal watercraft industry, and as used in the present application, the term sponson refers to a device having a generally hydrodynamic shape to aid in the watercraft in stabilizing straight ahead progress through the water and to aid in executing turns in the water. The personal watercraft sponsons are dimensioned and configured to have a fin or blade having an outwardly extending edge that penetrates below the water level during normal use. The personal watercraft""s sponson will penetrate below the water surface when the personal watercraft is at rest, in calm water, even with no rider on board. The sponson typically has an outwardly extending lower surface that rides on the water when the boat is planing.
Sponsons provide lift at the rear of the personal watercraft, acting to force the nose down to provide a degree of aggressiveness. Sponsons that provide harder, sharper cornering often also provide decreased straight line stability. The more aggressive design often has a xe2x80x9ctippyxe2x80x9d feeling when the rider shifts their weight. This tippy feeling is accepted by experienced drivers, but maybe unsettling to inexperienced drivers. Sponsons are typically designed together with the personal watercraft hull, for a particular model and year. Various considerations go into the hull and sponson design, including the desired degree of stability, desired lift provided by the sponson, and the degree of aggressiveness desired for that model and model year. Different drivers desiring different features can select varying personal watercraft having the desired handling characteristics.
What would be desirable are personal watercraft having sponsons which can vary according to the desired handling characteristics of the driver. What would be advantageous are sponsons which can be changed from an aggressive handling mode to a gentle riding mode.
The present invention provides ventilated sponsons, personal watercraft having ventilated sponsons, and methods for changing the handling characteristics of personal watercraft by forming holes in the sponsons. The present invention provides personal watercraft having sponsons that can extend outwardly and downwardly away from the hull of the personal watercraft, and have a downward and outward-most edge for penetrating beneath the water surface during use. The sponson body can have at least one hole formed through the body to relieve pressure formed along the underside of the sponson body. The holes"" diameter can vary with the particular embodiment. In some embodiments, the hole varies between about one-half inch and about one inch in diameter. The number of holes in some embodiments vary between one hole per sponson and about 5 holes per sponson.
Sponsons typically provide lift at the rear of a personal watercraft, raising the stern and lowering the bow, to provide a more aggressive handling and cornering machine. The outer edges of the sponson provide straightline stability by acting as a fixed rudder on either side of the hull. The outermost edges of the sponson also provide for tighter cornering by digging into the water during turns. In some situations, the driver may wish for improved straightline stability for a particular machine. Rather than being stuck with the particular handling characteristics of the particular personal watercraft, the present invention provides methods for adjusting the handling characteristics of the personal watercraft. Holes can be formed through the sponson body, to the underside of the sponson, to bleed off pressure formed along the underside of the sponson. In normal use, when the personal watercraft is planing, substantial water pressure is built up under the sponson, with a sponson horizontal surface typically riding on the surface of the water. Holes can be formed through the sponson body to allow a spray of water to exit through the hole, thereby relieving the pressure in the rear of the watercraft, thereby raising the nose of the watercraft. In some watercraft, the holes are between about one-half inch and one inch in diameter. In some sponsons, the holes have a pitch of about 10 degrees upward from a rearward facing horizontal direction and an outward angle of about 30 degrees away from a directly rearward facing orientation.